Cryopump

Abstract

The invention discloses a low-temperature pump which comprises a middle bearing provided with a containing cavity, a first opening is formed in the middle bearing of the containing cavity, an impeller is contained in the containing cavity, and the middle bearing is provided with a liquid inlet end and a liquid outlet end; the pump cover is arranged at the first opening; the isolation sleeve is arranged on the middle bearing; the rotating shaft is arranged on the middle bearing through a pair of ultralow-temperature bearings, the middle bearing is provided with a main channel communicated with the containing cavity and the isolation sleeve, the pair of ultralow-temperature bearings is located in the main channel, and the front end of the rotating shaft is connected with the impeller; the fan is arranged on the rotating shaft and located between the pair of ultralow-temperature bearings; the inner magnetic assembly is contained in the isolation sleeve, and the rear end of the rotating shaft is connected with the inner magnetic assembly; the outer magnetic assembly is arranged on the periphery of the isolation sleeve and is connected with the motor; wherein the fan is configured to suck fluid in the isolation sleeve into the main channel in the rotating process, the middle bearing is provided with a first liquid passing channel and a second liquid passing channel, the first liquid passing channel is communicated with the containing cavity and the isolation sleeve, and the second liquid passing channel is communicated with the main channel and the isolation sleeve.

Description

Technical Field

[0001] The present invention relates to the technical field of pumps, and in particular to a cryogenic pump. Background Art

[0002] Cryogenic pumps are used to pump cryogenic liquids (liquid nitrogen). When the cryogenic pump is working, when the temperature inside the pump is higher than minus 196 degrees Celsius, the liquid nitrogen will vaporize, causing gas to be generated inside the pump. The accumulation of gas in the pump will cause cavitation and damage the internal components of the pump, which is not desirable.

[0003] In the prior art, workers usually need to manually operate the exhaust of cryopumps and open the exhaust valve regularly. The above method has the disadvantages of not being able to achieve real-time exhaust and posing safety hazards. Workers' hands are easily splashed or frostbitten by liquid nitrogen. Therefore, it is necessary to improve the prior art to overcome the above defects in the prior art. Summary of the invention

[0004] The invention provides a cryogenic pump with good exhaust effect.

[0005] In order to achieve the above-mentioned purpose, the present invention proposes a cryogenic pump, comprising: a middle bearing, which is formed with a receiving cavity, the receiving cavity is formed with a first opening at the front end of the middle bearing, an impeller is received in the receiving cavity, the middle bearing has a liquid inlet end and a liquid outlet end connected to the receiving cavity; a pump cover, a sealing cover is arranged at the first opening; an isolation sleeve is arranged at the rear end of the middle bearing away from the pump cover; a rotating shaft is arranged on the middle bearing through a pair of ultra-low temperature bearings, the middle bearing is provided with a main channel connecting the receiving cavity and the isolation sleeve, the pair of ultra-low temperature bearings are located in the main channel, and the front end of the rotating shaft is connected to the impeller The fan is connected to the wheel; the fan is arranged on the rotating shaft and rotates with the rotating shaft, and the fan is located between the pair of ultra-low temperature bearings; the inner magnetic component is accommodated in the isolation sleeve, and the rear end of the rotating shaft is connected to the inner magnetic component; the outer magnetic component is arranged on the outer periphery of the isolation sleeve and connected to the motor; wherein the fan is configured to suck the fluid in the isolation sleeve into the main channel during rotation, and the middle bearing is provided with a first liquid passage and a second liquid passage, the first liquid passage connects the receiving chamber and the isolation sleeve, and the second liquid passage connects the main channel and the isolation sleeve.

[0006] Preferably, the front end of the inner magnetic component close to the middle bearing is axially recessed to form an inner magnetic cavity, the rear end of the middle bearing extends into the inner magnetic cavity, and the liquid inlet port of the main channel is located in the inner magnetic cavity; Among them, a thread groove distributed along an axial spiral is provided on the outer peripheral wall of the part of the middle bearing extending into the inner magnetic concave cavity. When the inner magnetic component rotates driven by the outer magnetic component, the fluid between the thread groove and the cavity wall of the inner magnetic concave cavity is forced to flow into the inner magnetic concave cavity at an accelerated speed.

[0007] Preferably, the rotating shaft is further provided with a positioning sleeve located in the inner magnetic concave cavity, the front end of the positioning sleeve abuts against the rear ultra-low temperature bearing of the pair of ultra-low temperature bearings away from the impeller, and the rear end of the positioning sleeve abuts against the bottom of the inner magnetic concave cavity; Wherein, a first step groove cooperating with the rear ultra-low temperature bearing is formed on the hole wall of the main channel.

[0008] Preferably, the bearing on the side close to the impeller in the pair of ultra-low temperature bearings is a front ultra-low temperature bearing, and a front bearing mounting structure for limiting the front ultra-low temperature bearing is further provided in the main channel; The front bearing mounting structure comprises a bearing ring seat fixedly arranged in the main channel, the bearing ring seat is provided with a step hole penetrating therethrough in the axial direction, the step hole enables the bearing ring seat to have a first hole portion close to the impeller and a second hole portion farther from the impeller than the first hole portion, the front ultra-low temperature bearing is arranged in the first hole portion, the front end of the bearing ring seat close to the impeller is detachably provided with a bearing pressure cover, and the bearing pressure cover abuts against the front end of the front ultra-low temperature bearing; Among them, the bearing cover has a cover center hole, the impeller includes a sleeve and a wheel portion formed on the outer periphery of the sleeve, the outer periphery of the wheel portion is provided with a plurality of blades, the axial thickness of the wheel portion is smaller than the axial thickness of the sleeve, and the rear end of the sleeve passes through the cover center hole and abuts against the front end of the front ultra-low temperature bearing.

[0009] Preferably, the second liquid passage has a second liquid outlet, which is located on the hole wall of the main channel, wherein the second liquid outlet is located between the fan and the front ultra-low temperature bearing of the pair of ultra-low temperature bearings close to the impeller.

[0010] Preferably, the first liquid passage is inclined relative to the rotating shaft, and the first liquid passage has a first liquid inlet and a first liquid outlet, the first liquid inlet is formed on the cavity wall of the accommodating cavity and is distributed close to the liquid outlet end, wherein the first liquid outlet is distributed lower than the first liquid inlet.

[0011] Preferably, the outer diameter of the portion of the center bearing located within the isolation sleeve is in a decreasing state.

[0012] Preferably, the pump cover is provided with an avoidance cavity for accommodating the front end of the rotating shaft, and the avoidance cavity and the accommodating cavity are surrounded to form a pump cavity of the cryopump; Among them, the pump cover is also provided with a third liquid passage connecting the avoidance chamber and the receiving chamber, the third liquid inlet of the third liquid passage is distributed close to the liquid outlet end, and the third liquid outlet of the third liquid passage is distributed lower than the third liquid inlet.

[0013] Preferably, the front end of the rotating shaft is also provided with an anti-loosening gasket and an anti-loosening nut, the anti-loosening gasket abuts against the front end of the impeller, and the anti-loosening nut abuts against the front end of the anti-loosening gasket, wherein the former of the pair of ultra-low temperature bearings abuts against the rear end of the impeller.

[0014] Preferably, a bracket is provided on the outer periphery of the outer magnetic assembly, and the bracket is connected to the housing of the motor and the middle bearing, wherein after the bracket is connected to the middle bearing, the isolation sleeve is pressed onto the middle bearing; A sealing structure is provided between the center bearing and the isolation sleeve, the sealing structure is an annular structure with a closed space inside, a pair of hard rubber rings are provided in the closed space, an elastic member is provided between the pair of hard rubber rings, and the elastic member is configured to provide an elastic force in the axial direction so that the pair of hard rubber rings are respectively abutted against the two ends of the annular structure; Wherein, the inner ring wall and the outer ring wall of the sealing structure are made of flexible material, and the inner ring wall and the outer ring wall of the sealing structure can generate elastic deformation when subjected to external force.

[0015] The technical solution provided by the present invention has the following advantages: In this embodiment, after the fan rotates, it can make the main channel present a negative pressure state, thereby being able to suck the liquid nitrogen in the isolation sleeve into the main channel, accelerating the flow of liquid nitrogen from the isolation sleeve to the receiving chamber, thereby accelerating the circulation speed of liquid nitrogen in the cryopump, which is beneficial to the discharge of gas through the liquid inlet and outlet ends, and has the advantage of good exhaust effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0017] Figure 1 A schematic diagram of the three-dimensional structure of the cryopump provided by the present invention; Figure 2A schematic cross-sectional view of a portion of the structure of the cryopump provided by the present invention; Figure 3 for Figure 2 Schematic diagram of the enlarged structure of the A area in the middle; Figure 4 A schematic diagram of the exploded structure of the cryopump provided by the present invention; Figure 5 It is a schematic diagram of the cross-sectional structure between the center bearing and the pump cover; Figure 6 This is a schematic diagram of the three-dimensional structure of the center bearing at the first viewing angle; Figure 7 is a schematic diagram of the three-dimensional structure of the inner magnetic component; Figure 8 This is a schematic diagram of the three-dimensional structure of the middle bearing in the second viewing angle; Fig. 9 Schematic diagram of the three-dimensional structure of the isolation sleeve; Fig.10 is a cross-sectional schematic diagram of the front bearing mounting structure; Fig.11 is a cross-sectional schematic diagram of the bearing ring seat; Fig.12 It is a schematic diagram of the three-dimensional structure of the bearing gland; Fig.13 Schematic diagram of the three-dimensional structure of the impeller; Fig.14 It is a cross-sectional schematic diagram of the sealing structure. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] It should be noted that if a directional indication is involved in the embodiments of the present invention, the directional indication is only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0020] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the meaning of "and / or" appearing in the full text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0021] The present invention provides a cryopump for pumping cryogenic liquids. The cryopump may be a liquid nitrogen pump, or a liquid helium pump, a cryogenic circulation pump, a cryogenic adsorption pump, etc. When the cryopump is a liquid nitrogen pump, the cryogenic liquid is liquid nitrogen; when the cryopump is a liquid helium pump, the cryogenic liquid is liquid helium. The following description takes the case where the cryopump is a liquid nitrogen pump as an example. However, based on the above description, it can be seen that the protection scope of the present invention is not limited thereby.

[0022] like Figures 1 to 4 As shown, the cryopump includes a center bearing 100, a pump cover 200, an impeller 120, an isolation sleeve 400, a rotating shaft 300, a fan 320, an inner magnetic assembly 500, an outer magnetic assembly 600 and a motor 700. The pump cover 200 and the motor 700 are respectively located at the front and rear ends of the cryopump. In order to facilitate the description of the positional relationship between the various components, the direction where the pump cover 200 is located is defined as the front end of the cryopump, the direction where the motor 700 is located is defined as the rear end of the cryopump, and the axial direction of the rotating shaft 300 is defined as the axial direction of the cryopump. The "axial direction" appearing below refers to the axial direction of the cryopump.

[0023] like Figure 5 and Figure 6 As shown, a receiving chamber 110 and a main channel 130 are formed on the middle bearing 100, and the receiving chamber 110 and the main channel 130 are connected in the axial direction to penetrate the middle bearing 100 in the axial direction. Among them, the receiving chamber 110 is formed with a first opening at the front end of the middle bearing 100, and the middle bearing 100 has a liquid inlet end 111 and a liquid outlet end 112 connected to the receiving chamber 110, and the liquid inlet end 111 is used to pump liquid nitrogen into the receiving chamber 110, and the liquid outlet end 112 is used to pump liquid nitrogen out of the receiving chamber 110. The receiving chamber 110 contains an impeller 120, and the pump cover 200 sealing cover is arranged at the first opening, which is used to seal the impeller 120 in the receiving chamber 110.

[0024] like Figure 2As shown, the rotating shaft 300 is arranged on the middle bearing 100 through a pair of ultra-low temperature bearings 310, and the pair of ultra-low temperature bearings 310 are located in the main channel 130. The front end of the rotating shaft 300 is located in the receiving chamber 110 and is connected to the impeller 120. The fan 320 is arranged on the rotating shaft 300 and is located between the pair of ultra-low temperature bearings 310, and the fan 320 rotates with the rotating shaft 300. Among them, the pair of ultra-low temperature bearings 310 includes a front ultra-low temperature bearing 312 close to the side of the impeller 120 and a rear ultra-low temperature bearing 311 away from the side of the impeller 120, and the fan 320 is located between the front ultra-low temperature bearing 312 and the rear ultra-low temperature bearing 311. The outer peripheries of the rear ultra-low temperature bearing 311 and the front ultra-low temperature bearing 312 are provided with a tightening ring 360, and the tightening ring 360 is used to clamp the rear ultra-low temperature bearing 311 and the front ultra-low temperature bearing 312.

[0025] The isolation sleeve 400 is disposed on the middle bearing 100 and is located at the rear end of the middle bearing 100 away from the pump cover 200. The main channel 130 on the middle bearing 100 connects the receiving chamber 110 and the isolation sleeve 400. The isolation sleeve 400 accommodates the inner magnetic assembly 500, and the rear end of the rotating shaft 300 is located in the isolation sleeve 400 and connected to the inner magnetic assembly 500.

[0026] The middle bearing 100 is also provided with a first liquid passage 140 and a second liquid passage 150. The first liquid passage 140 connects the receiving chamber 110 with the isolation sleeve 400, and the second liquid passage 150 connects the main channel 130 with the isolation sleeve 400. The liquid nitrogen in the receiving chamber 110 enters the isolation sleeve 400 through the first liquid passage 140, and the liquid nitrogen in the isolation sleeve 400 enters the receiving chamber 110 through the main channel 130. There are two ways for the liquid nitrogen in the isolation sleeve 400 to enter the main channel 130: the first way is to enter the main channel 130 through the second liquid passage 150; the second way is to enter the main channel 130 through the gap on the rear ultra-low temperature bearing 311.

[0027] Specifically, Figure 5 As shown, the first liquid passage 140 has a first liquid inlet 141 and a first liquid outlet 142. The first liquid passage 140 is tilted relative to the rotating shaft 300, and the first liquid outlet 142 is lower than the first liquid inlet 141. The first liquid inlet 141 is formed on the wall of the receiving cavity 110 and is close to the liquid outlet 112. Considering the high pressure at the liquid outlet 112, the first liquid inlet 141 is close to the liquid outlet 112, which can effectively improve the efficiency of liquid nitrogen entering the isolation sleeve 400. The tilted arrangement of the first liquid passage 140 can further accelerate the entry of liquid nitrogen into the isolation sleeve 400, and the isolation sleeve 400 has a high liquid entry efficiency.

[0028] An external magnetic component 600 is provided on the outer periphery of the isolation sleeve 400, and the external magnetic component 600 cooperates with the internal magnetic component 500 in the isolation sleeve 400 by magnetic force. The external magnetic component 600 is connected to the motor 700. Specifically, the motor 700 has an output shaft, and the external magnetic component 600 is connected to the output shaft of the motor 700. When the output shaft of the motor 700 rotates, the external magnetic component 600 is driven to rotate. After the external magnetic component 600 rotates, the internal magnetic component 500 is driven to rotate synchronously. Since the internal magnetic component 500 is fixedly connected to the rotating shaft 300, the rotating shaft 300 rotates under the drive of the internal magnetic component 500, and the rotating shaft 300 rotates, and the rotating shaft 300 drives the fan 320 and the impeller 120 thereon to rotate. It is worth noting that a large amount of heat will be generated in the process of the external magnetic component 600 driving the internal magnetic component 500 to rotate. The above heat is mainly concentrated in the isolation sleeve 400, causing the temperature of the liquid nitrogen in the isolation sleeve 400 to rise, thereby generating a vaporization phenomenon.

[0029] The fan 320 can suck the fluid (a mixture of liquid nitrogen and nitrogen) in the isolation sleeve 400 into the main channel 130 during rotation. This is because the fan 320 can make the main channel 130 in a negative pressure state after rotation, thereby being able to suck the fluid in the isolation sleeve 400 into the main channel 130, accelerating the flow of the fluid from the isolation sleeve 400 to the receiving chamber 110, and speeding up the circulation speed of the fluid in the isolation sleeve 400 in the cryogenic pump, which is conducive to the discharge of the vaporized gas through the liquid outlet 112.

[0030] In one embodiment, if Figure 7 As shown, the front end of the inner magnetic component 500 close to the middle bearing 100 is axially recessed to form an inner magnetic cavity 510, the rear end of the middle bearing 100 extends into the inner magnetic cavity 510, and the liquid inlet port 131 of the main channel 130 is located in the inner magnetic cavity 510. Among them, the outer peripheral wall of the portion of the middle bearing 100 extending into the inner magnetic cavity 510 is provided with a thread groove 160 distributed in an axial spiral. When the inner magnetic component 500 rotates driven by the outer magnetic component 600, the fluid between the thread groove 160 and the cavity wall of the inner magnetic cavity 510 is forced to flow into the inner magnetic cavity 510 at an accelerated speed. In other words, the cooperation between the inner magnetic cavity 510 and the thread groove 160 can accelerate the flow speed of the fluid, which is beneficial to the discharge of gas.

[0031] Specifically, the center bearing 100 has a first portion located outside the isolation sleeve 400 and a second portion extending into the isolation sleeve 400. The receiving cavity 110 is provided on the first portion. A portion of the main channel 130 is located on the first portion, and another portion is located on the second portion. The thread groove 160 is provided on the outer peripheral wall of the rear end of the second portion. Figure 8 and Fig. 9As shown, a first step portion 170 and a second step portion 180 are also provided on the outer peripheral wall of the above-mentioned second part. The first step portion 170 cooperates with the convex ring portion 420 at the open end 410 of the isolation sleeve 400 to limit the installation of the isolation sleeve 400. The second step portion 180 is located inside the isolation sleeve 400.

[0032] The outer diameter of the first step portion 170 is greater than the outer diameter of the second step portion 180. The first step portion 170 and the second step portion 180 reduce the outer diameter of the second portion of the center support 100, thereby increasing the space for liquid nitrogen to flow. Figure 2 , Figure 7 and Figure 8 As shown, the above-mentioned enlarged space refers to the space between the first liquid outlet 142 and the front end 511 of the inner magnetic assembly 500 . The above-mentioned enlarged space can provide space for storing liquid nitrogen, which is conducive to the flow of liquid nitrogen in the entire isolation sleeve 400 .

[0033] It is worth noting that Figure 2 and Figure 5 As shown, the second liquid passage 150 has a second liquid outlet 151 and a second liquid inlet 152, wherein the second liquid outlet 151 is located on the hole wall of the main channel 130, and the second liquid inlet 152 is located on the circumferential outer wall of the middle bearing. The second liquid outlet 151 is located between the fan 320 and the front ultra-low temperature bearing 312, that is, the second liquid outlet 151 of the second liquid passage 150 is located downstream of the fan 320.

[0034] There are two paths for the fluid in the isolation sleeve 400 to enter the main channel 130. One path is that the fluid enters the main channel 130 through the liquid inlet port 131 and the rear ultra-low temperature bearing 311. In this case, the fluid needs to flow through the fan 320. The other path is that part of the fluid in the isolation sleeve 400 flows directly to the downstream of the fan 320 through the second liquid passage 150. In this case, part of the fluid can avoid the fan 320 and enter the main channel 130. Therefore, the pressure on the fan 320 can be effectively reduced, which is very beneficial to the normal operation of the fan 320.

[0035] Furthermore, the second liquid passage 150 is arranged perpendicular to the rotating shaft 300 and is distributed closer to the fan 320 relative to the front ultra-low temperature bearing 312 to shorten the length of the second liquid passage 150 as much as possible, thereby making it easier for the fluid to enter the main channel 130 from the isolation sleeve 400.

[0036] Regarding the axial limit of the rear cryogenic bearing 311, Figure 2As shown, the rotating shaft 300 is also sleeved with a positioning sleeve 330 located in the inner magnetic cavity 510, the front end of the positioning sleeve 330 abuts against the rear ultra-low temperature bearing 311, and the rear end of the positioning sleeve 330 abuts against the cavity bottom of the inner magnetic cavity 510, and a first step groove 132 that cooperates with the rear ultra-low temperature bearing 311 is formed on the hole wall of the main channel 130. Under the joint action of the above-mentioned positioning sleeve 330 and the first step groove 132, the axial limitation of the rear ultra-low temperature bearing 311 can be achieved. Among them, the positioning sleeve 330 can ensure that there is a predetermined spacing between the rear end of the second part of the middle bearing 100 and the cavity bottom of the inner magnetic cavity 510 in the axial direction to form a buffer zone, which is conducive to the liquid nitrogen in the inner magnetic cavity 510 entering the main channel 130 through the liquid inlet port 131.

[0037] Furthermore, a front bearing mounting structure 800 for limiting the front cryogenic bearing 312 is also provided in the main channel 130. Figures 10 to 12 As shown, the front bearing mounting structure 800 includes a bearing ring seat 810 fixed in the main channel 130, and the bearing ring seat 810 is provided with a step hole penetrating the bearing ring seat 810 in the axial direction. The step hole enables the bearing ring seat 810 to have a first hole portion 811 close to the impeller 120 and a second hole portion 812 farther from the impeller 120 than the first hole portion 811. The front ultra-low temperature bearing 312 is arranged in the first hole portion 811. The front end of the bearing ring seat 810 close to the impeller 120 is detachably provided with a bearing gland 820, and the bearing gland 820 abuts against the front end of the front ultra-low temperature bearing 312. Among them, the bearing gland 820 has a gland center hole 821, and a backing ring 822 is provided at the rear end of the bearing gland 820. The inner ring diameter of the backing ring 822 is equal to the hole diameter of the gland center hole 821 and is coaxially distributed, and the backing ring 822 abuts against the front ultra-low temperature bearing 312. Therefore, the front cryogenic bearing 312 is axially positioned through the bearing ring seat 810 and the bearing cover 820 .

[0038] Regarding the axial positioning of the impeller 120, Fig.13 As shown, the impeller 120 includes a sleeve 121 and a wheel portion 122 formed on the outer periphery of the sleeve 121. A plurality of blades 123 are provided on the outer periphery of the wheel portion 122. The axial thickness of the wheel portion 122 is smaller than the axial thickness of the sleeve 121. After the rear end of the sleeve 121 passes through the center hole 821 of the pressure cover, it abuts against the front end of the front ultra-low temperature bearing 312.

[0039] like Figure 2As shown, the front end of the rotating shaft 300 is also provided with a locking washer 340 and a locking nut 350, the locking washer 340 abuts against the front end of the impeller 120, and the locking nut 350 abuts against the front end of the locking washer 340, wherein the front ultra-low temperature bearing 312 abuts against the rear end of the impeller 120. Thus, the axial position of the impeller 120 can be limited. During use, when it is found that the impeller 120 moves in the axial direction, the axial locking can be achieved by tightening the locking nut 350, and the adjustment is more convenient.

[0040] Furthermore, if Figure 5 As shown, the pump cover 200 is provided with an avoidance chamber 210 for accommodating the front end of the rotating shaft 300, and the avoidance chamber 210 and the accommodating chamber 110 are surrounded to form the pump chamber of the cryopump. The pump cover 200 is also provided with a third liquid passage 220 connecting the avoidance chamber 210 and the accommodating chamber 110, and the third liquid inlet of the third liquid passage 220 is distributed close to the liquid outlet 112, and the third liquid outlet of the third liquid passage 220 is distributed lower than the third liquid inlet. Therefore, it is beneficial for the liquid nitrogen at the liquid outlet 112 to be quickly delivered into the avoidance chamber 210, so that the liquid nitrogen can flow continuously and quickly in the cryopump to facilitate the gas to be discharged outward.

[0041] In order to protect the outer magnetic assembly 600, a bracket 710 is provided on the outer periphery of the outer magnetic assembly 600. Figure 2 As shown, the bracket 710 connects the housing of the motor 700 and the middle bearing 100. The middle bearing 100, the pump cover 200 and the bracket 710 are connected by long bolts 720. After the middle bearing 100, the pump cover 200 and the bracket 710 are connected, the isolation sleeve 400 is pressed against the middle bearing 100 by the bracket 710, thereby realizing the installation of the isolation sleeve 400.

[0042] As can be seen from the above, the spacer sleeve 400 and the center bearing 100 do not need to be connected by bolts, which simplifies the structure of the spacer sleeve 400. More importantly, in order to adapt to the low temperature environment, the spacer sleeve 400 is made of ceramic material. Since the ceramic material is brittle, it is difficult to process. When processing some holes, the spacer sleeve 400 is prone to breakage.

[0043] In order to prevent the liquid nitrogen in the isolation sleeve 400 from leaking out, a sealing structure 900 is provided between the center bearing 100 and the isolation sleeve 400. Fig.14As shown, the sealing structure 900 is an annular structure with a closed space inside, and the sealing structure 900 is arranged at the first step portion 170. The outer ring of the sealing structure 900 abuts against the inner wall of the bracket 710, and a positioning shoulder 711 is formed on the inner wall of the bracket 710. The positioning shoulder 711 abuts against the rear end of the convex ring portion 420, the convex ring portion 420 abuts against the rear end of the sealing structure 900, and the sealing structure 900 abuts against the front end of the convex ring portion 420. The sealing structure 900 is located in a space surrounded by the middle support 100, the bracket 710, and the convex ring portion 420.

[0044] A pair of hard rubber rings 930 are arranged in the above-mentioned closed space of the sealing structure 900, and an elastic member 940 is arranged between the pair of hard rubber rings 930. The elastic member 940 is preferably a spring, and the elastic member 940 is used to provide an elastic force in the axial direction, so that the pair of hard rubber rings 930 are respectively against the two ends of the annular structure. Among them, the inner ring wall and the outer ring wall of the sealing structure 900 are made of flexible materials, and the inner ring wall and the outer ring wall of the sealing structure 900 can produce elastic deformation when subjected to external force. When the middle bearing 100 is connected to the bracket 710, the inner ring wall and the outer ring wall of the sealing structure 900 are compressed in the axial direction, and the inner ring wall and the outer ring wall produce a certain deformation in the radial direction, so that the sealing structure 900 can better seal the gap between the middle bearing 100 and the isolation sleeve 400 to prevent liquid nitrogen from leaking out.

[0045] Specifically, the sealing structure 900 includes an outer flexible ring 910, an inner flexible ring 920 arranged inside the outer flexible ring 910, a pair of the above-mentioned hard rubber rings 930 arranged between the outer flexible ring 910 and the inner flexible ring 920, the above-mentioned elastic member 940 arranged between the pair of hard rubber rings 930, and sealing gaskets 950 arranged at both ends of the outer flexible ring 910 and the inner flexible ring 920.

[0046] The outer flexible ring 910 is the outer ring wall of the sealing structure 900, and the inner flexible ring 920 is the inner ring wall of the sealing structure 900. The outer flexible ring 910 and the inner flexible ring 920 can produce elastic deformation when subjected to external force, and the two ends of the outer flexible ring 910 and the inner flexible ring 920 are flushly distributed. A pair of sealing gaskets 950 are provided, which are respectively arranged at the two ends of the outer flexible ring 910 and the inner flexible ring 920 by gluing.

[0047] The outer flexible ring 910 is coaxially distributed with the inner flexible ring 920, and there is a space between the outer ring of the inner flexible ring 920 and the inner ring of the outer flexible ring 910. The sealing gasket 950, the outer flexible ring 910 and the inner flexible ring 920 are jointly arranged to form the above-mentioned closed space. A pair of hard rubber rings 930 are sleeved on the outer periphery of the inner flexible ring 920 and are located in the closed space. The pair of hard rubber rings 930 are spaced apart in the axial direction, and the elastic member 940 is disposed between the pair of hard rubber rings 930, and the hard rubber ring 930 is in contact with the sealing gasket 950. The elastic member 940 makes the two ends of the sealing structure 900 contact with the middle bearing 100 and the isolation sleeve 400 respectively, thereby ensuring the sealing performance of the sealing structure 900.

[0048] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure made using the contents of the present invention specification and drawings, or directly or indirectly used in other related technical fields, is also included in the patent protection scope of the present invention.

Claims

1. A cryogenic pump, characterized in that: include: A middle support (100) is formed with a receiving cavity (110), wherein the receiving cavity (110) is formed with a first opening at the front end of the middle support (100), an impeller (120) is received in the receiving cavity (110), and the middle support (100) has a liquid inlet end (111) and a liquid outlet end (112) which are in communication with the receiving cavity (110); A pump cover (200), wherein the sealing cover is arranged at the first opening; An isolation sleeve (400) is arranged at a rear end of the middle support (100) away from the pump cover (200); A rotating shaft (300) is arranged on the middle bearing (100) via a pair of ultra-low temperature bearings (310); the middle bearing (100) is provided with a main channel (130) communicating with the receiving cavity (110) and the isolation sleeve (400); the pair of ultra-low temperature bearings (310) are located in the main channel (130); and the front end of the rotating shaft (300) is connected to the impeller (120); a fan (320) disposed on the rotating shaft (300) and rotating together with the rotating shaft (300), wherein the fan (320) is located between the pair of ultra-low temperature bearings (310); An internal magnetic component (500) is accommodated in the isolation sleeve (400), and the rear end of the rotating shaft (300) is connected to the internal magnetic component (500); An external magnetic component (600) is arranged on the outer periphery of the isolation sleeve (400) and is connected to the motor (700); The fan (320) is configured to suck the fluid in the isolation sleeve (400) into the main channel (130) during rotation, and the middle support (100) is provided with a first liquid passage (140) and a second liquid passage (150), wherein the first liquid passage (140) connects the receiving cavity (110) and the isolation sleeve (400), and the second liquid passage (150) connects the main channel (130) and the isolation sleeve (400).

2. The cryopump according to claim 1, wherein: The front end of the inner magnetic component (500) close to the middle support (100) is axially recessed to form an inner magnetic cavity (510); the rear end of the middle support (100) extends into the inner magnetic cavity (510); and the liquid inlet port (131) of the main channel (130) is located in the inner magnetic cavity (510); The outer peripheral wall of the portion of the middle bearing (100) extending into the inner magnetic cavity (510) is provided with a thread groove (160) distributed in an axial spiral, and when the inner magnetic component (500) rotates driven by the outer magnetic component (600), the fluid between the thread groove (160) and the cavity wall of the inner magnetic cavity (510) is forced to flow into the inner magnetic cavity (510) at an accelerated speed.

3. The cryopump according to claim 2, wherein: The rotating shaft (300) is also sleeved with a positioning sleeve (330) located in the inner magnetic concave cavity (510), the front end of the positioning sleeve (330) abuts against a rear ultra-low temperature bearing (311) of the pair of ultra-low temperature bearings (310) which is located away from the impeller (120), and the rear end of the positioning sleeve (330) abuts against the bottom of the inner magnetic concave cavity (510); Wherein, a first step groove (132) cooperating with the rear ultra-low temperature bearing (311) is formed on the hole wall of the main channel (130).

4. The cryopump according to claim 1, wherein: The bearing on the side of the pair of ultra-low temperature bearings (310) closer to the impeller (120) is a front ultra-low temperature bearing (312), and a front bearing mounting structure (800) for limiting the position of the front ultra-low temperature bearing (312) is also provided in the main channel (130); The front bearing mounting structure (800) comprises a bearing ring seat (810) fixedly arranged in the main channel (130), the bearing ring seat (810) being provided with a step hole penetrating the bearing ring seat (810) in the axial direction, the step hole enabling the bearing ring seat (810) to have a first hole portion close to the impeller (120) and a second hole portion farther from the impeller (120) than the first hole portion, the front ultra-low temperature bearing (312) being arranged in the first hole portion, the front end of the bearing ring seat (810) close to the impeller (120) being detachably provided with a bearing pressure cover (820), the bearing pressure cover (820) being in abutment with the front end of the front ultra-low temperature bearing (312); The bearing gland (820) has a gland center hole (821), the impeller (120) comprises a sleeve (121), and a wheel portion (122) formed on the outer periphery of the sleeve (121), a plurality of blades (123) are provided on the outer periphery of the wheel portion (122), the axial thickness of the wheel portion (122) is smaller than the axial thickness of the sleeve (121), and the rear end of the sleeve (121) abuts against the front end of the front ultra-low temperature bearing (312) after passing through the gland center hole (821).

5. The cryopump according to claim 1, wherein: The second liquid passage (150) has a second liquid outlet (151), and the second liquid outlet (151) is located on the hole wall of the main channel (130), wherein the second liquid outlet (151) is located between the fan (320) and a front ultra-low temperature bearing (312) of the pair of ultra-low temperature bearings (310) close to the impeller (120).

6. The cryopump according to claim 1, wherein: The first liquid passage (140) is arranged obliquely relative to the rotating shaft (300), and the first liquid passage (140) has a first liquid inlet (141) and a first liquid outlet (142), wherein the first liquid inlet (141) is formed on the cavity wall of the receiving cavity (110) and is distributed close to the liquid outlet end (112), wherein the first liquid outlet (142) is distributed lower than the first liquid inlet (141).

7. The cryopump according to claim 1, wherein: The outer diameter of the portion of the center bearing (100) located inside the isolation sleeve (400) is in a decreasing state.

8. The cryopump according to claim 1, wherein: The pump cover (200) is provided with an avoidance cavity (210) for accommodating the front end of the rotating shaft (300), and the avoidance cavity (210) and the accommodating cavity (110) are surrounded to form a pump cavity of the cryopump; The pump cover (200) is further provided with a third liquid passage (220) connecting the avoidance chamber (210) and the receiving chamber (110); a third liquid inlet of the third liquid passage (220) is arranged close to the liquid outlet end (112); and a third liquid outlet of the third liquid passage (220) is arranged lower than the third liquid inlet.

9. The cryopump according to claim 1, wherein: The front end of the rotating shaft (300) is also provided with an anti-loosening gasket (340) and an anti-loosening nut (350), wherein the anti-loosening gasket (340) abuts against the front end of the impeller (120), and the anti-loosening nut (350) abuts against the front end of the anti-loosening gasket (340), wherein the former of the pair of ultra-low temperature bearings (310) abuts against the rear end of the impeller (120).

10. The cryopump according to claim 1, wherein: A bracket (710) is provided on the outer periphery of the external magnetic assembly (600), and the bracket (710) is connected to the outer shell of the motor (700) and the middle bearing (100), wherein after the bracket (710) is connected to the middle bearing (100), the isolation sleeve (400) is pressed onto the middle bearing (100); A sealing structure (900) is provided between the center bearing (100) and the isolation sleeve (400); the sealing structure (900) is an annular structure having a sealed space inside; a pair of hard rubber rings (930) are provided in the sealed space; an elastic member (940) is provided between the pair of hard rubber rings (930); the elastic member (940) is configured to provide an elastic force in the axial direction so that the pair of hard rubber rings (930) are respectively in contact with two ends of the annular structure; The inner ring wall and the outer ring wall of the sealing structure (900) are made of a flexible material, and the inner ring wall and the outer ring wall of the sealing structure (900) are capable of elastic deformation when subjected to an external force.

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